The model proposed by Henrich (2004), which is often cited as a theoretical basis for understanding the role of demography in the cumulative cultural evolution of technology, is expounded for general readers and reanalyzed through a novel approach based on the concept of innovation rate. In this analysis, the model is generalized to allow a broader class of distributions for the distribution of individual skill levels, while preceding studies explored only the cases of Gumbel, logistic, and normal distributions. It is revealed that the expected number of innovators per generation is a key determinant of the sign and tempo of technological growth. In particular, the maximum skill level in a population grows cumulatively when the expected number of innovators per generation exceeds a certain threshold. Based on the results of the theoretical discussion, existing experimental tests of the model and related demographic hypotheses are reevaluated in the latter half of the article, while remarks are made on future possible tests of the model from a quantitative perspective.

Cumulative cultural evolution is the process of cultural change where knowledge and/or skills accumulate across multiple generations through cultural transmission. It is a characteristic feature specific to human culture, enabling us to produce and improve complex technologies beyond individual capabilities. Various experiments have been conducted on the cumulative cultural evolution of technology. However, due to the lack of specificity in general definitions, the operational definitions necessary for experimental design often differed from study to study. Hence, we introduce Buskell’s (2022) definition of cumulative cultural evolution as a highly concrete definition that is helpful for experimental design. Buskell proposed four types of definitions of improvement: adaptability, efficiency, complexity, and heterogeneity. Reviewing previous literature, we confirmed that these four types of definitions can be applied to previous experiments on cumulative cultural evolution, suggesting that Buskell's concrete definition is useful for those who plan to design an experiment on cumulative cultural evolution in future research. Additionally, we discuss how incorporating perspectives from social and cultural psychology could impact and advance research on cultural evolution.

In recent years, the concept and theory of niche construction, originally developed in evolutionary biology, have been increasingly embraced in the humanities and social sciences, at least partly connected by the study of cultural evolution. While niche construction theory is not mainstream in evolutionary biology, there are various reasons for its acceptance in the humanities and social sciences. This paper provides an overview of several trends relevant to niche construction theory, focusing on cultural evolution and related fields. Initially, I will review the terminology associated with niche construction theory and the ongoing debate surrounding it, including the extended evolutionary synthesis in evolutionary biology. Subsequently, I will explore why niche construction is gaining attention in the humanities and social sciences, providing examples of research on cultural and social niche construction. Finally, the paper will present several hypotheses linking niche construction and human evolution.

Helping behavior towards individuals with anxiety and worries often begins with “awareness,” which involves considering the potential from another individual’s appearance and contextual information. However, real-life support situations are not always those where information is clearly expressed. In this study, we defined early awareness as the empathic arousal that occurs when an observer detects low-intensity negative emotional expressions in others, and we examined the cognitive factors influencing this judgment. In a preliminary experiment, 18 videos expressing low-intensity negative emotions were created. In the main experiment, 52 university students were shown these videos in a sequence of 3 seconds each and were asked to identify the videos that caught their attention, providing reasons through free responses. The 583 free responses were classified into 16 items, and a generalized linear mixed model was used to analyze the presence or absence of awareness as the dependent variable. Five positive and six negative influencing factors were identified. This experiment provided insights into the characteristics of cognition and desirable attitudes for observers during the early stages of awareness, which are crucial for providing empathic support.

The present study used voluntary panel Web surveys to investigate the validity of the Multidimensional Perfectionism Cognition Inventory (MPCI: Kobori & Tanno, 2004). We conducted a two-wave panel survey of 520 Japanese adults in the Tokyo metropolitan area from March to April 2022. The results revealed the following: (1) Exploratory factor analysis (EFA) supported the three-factor structure congruent with previous studies. Still, EFA supported the two-factor structure using the Kaiser and Scree criteria. (2) Correlation analyses and partial correlation analyses between MPCI and two existing scales (ATQ-R and I-PANAS-SF) confirmed the validity of the two subscales of MPCI, “personal standard” and “concern over mistakes.” (3) Structural equation modeling with a cross-lagged effects model showed that the “pursuit of perfection” was related to the subsequent two factors. However, the other two factors were unrelated to the subsequent “pursuit of perfection.” These findings suggest that MPCI measures three factors with high inter-factor correlations and has sufficient validity in Japanese adults and that the “pursuit of perfection” is the factor corresponding to the abstract goal.

In Japan, the percentage of single adults has been increasing steadily since 1990. Although previous studies have identified socioeconomic factors as a reason for individuals remaining single, they have largely overlooked psychological factors. Thus, the present study explored psychological factors associated with singlehood, with a focus on attachment style. We analyzed data obtained from 3,568 men and women aged 29–39 years. Using logistic regression, we examined the effects of socioeconomic variables, which previous research had determined to affect marital experience, and the two dimensions of attachment (i.e., anxiety and avoidance) on marital experience. The results demonstrated that the two dimensions of attachment were associated with marital experience even when controlling for the socioeconomic variables. The study observed that the socioeconomic variables moderated these associations. The findings highlighted the importance of considering not only socioeconomic but also psychological factors as possible determinants of marital experience.

Memorable Tourism Experiences (MTEs) are experiences clearly remembered or recalled after an event has ended. This study aimed to determine the types of sightseeing trips, specific most memorable experiences, and the characteristics of MTEs by the age group of those that conducted the trips. A survey was conducted on 1,200 Japanese individuals to gather information about their most memorable sightseeing trips at different stages of their lives. Using analyses, MTEs were classified into nine groups: such as shared experiences with accompanying family and friends, novel experiences such as a first trip abroad, aesthetic experiences of natural scenery and gastronomy, and mobile experiences of traveling around Hokkaido and Kyushu. Analyses by age group indicated that MTEs also shifted with the life stage. Afterwards, we discussed the experiences with significant others at each life stage and concluded that milestone trips marking life transitions are more likely to be remembered.